Alaska Under Tsunami Advisory After Large Earthquake

A tsunami advisory is in effect for parts of the Alaska Peninsula following a large, underwater earthquake.

The National Oceanic and Atmospheric Administration initially issued a warning for coastal areas from Kennedy Entrance, about 40 miles southwest of Homer, to Unimak Pass, about 80 miles northeast of Unalaska. The warning has been downgraded to an advisory.

The warning came after a magnitude 7.3 earthquake hit about 54 miles south of Sand Point, Alaska, according to the U.S. Geological Survey. A major earthquake capable of “serious damage” is a quake of magnitude 7.0 to 7.9.

Earlier in the day, a magnitude 5.0 earthquake hit 45 miles southeast of Atka Village, Alaska.

“Coastal Alaska communities live with the most serious tsunami risk in the United States,” according to the Alaska Earthquake Center at the University of Alaska Fairbanks.

Tsunamis can be caused by “any large movement of land in or near the ocean,” including earthquakes, landslides, and volcanic eruptions, the center’s website says. There have been more than 15,000 earthquakes reported in Alaska this year.

Magnitude 7 to 8 earthquakes happen about once per year, according to Sea Grant Alaska.

The NOAA issues tsunami warnings for any seismic activity greater than magnitude 7.0, according to a NOAA informational sheet.

“Warnings are issued when the earthquake information or tsunami forecasts indicate that a wave over one meter in amplitude is expected, possible, or ongoing,” the info sheet said.

According to the NOAA’s U.S. Tsunami Warning System, “Tsunamis that cause damage or deaths near their source occur approximately twice per year. Tsunamis that cause damage or deaths on distant shores (more than 1,000 kilometers, 620 miles, away) occur about twice per decade.”